Changing altitude and re-adjusting FMC?

[mdavenport 0]

I am flying the 737 PIC using LNAV and VNAV. If I change altitude using Level Chg on the MCP should the FMC be altered to re-adjust the Top of Descent to take into account the new altitude?What is the correct procedure for this?ThanksMark

[Guest j-mo]

Yes, enter the new cruise altitude in the FMC. This allows the FMC to more accurately calculate the things it does, including TOD.

[Guest jshyluk]

That's pretty much it. I think one of the most important functions of the FMC is the Economy setting (ECON). Seeing as FSX uses virtual fuel we don't pay for, most virtual FMC's don't address this number, or if they do, it's window dressing.The ECON variable adjusts the algorythm for the most economical flight path given the wind, weight, speed restrictions, and waypoints. Usually, it's better at calculating fuel consumption for various manoeuvres than most sim-pilots. If you deviate from the FMC, then you are probably no longer flying the most economical route, although there's lots of valid reasons why you would want to do that. Sometimes, seeing if you can fit the aircraft under a bridge while inverted is valid, at least for flight sim. What the ECON number actually means, though, is above my pay grade. Each airline sets up their own number, but how they do that is unknown to me. If you can get your hands on a real-world airline flight manual with FMC instructions, you can find an explaination in there. Although from what I recall (I could be wrong here), the pilots are just given a number, and they plug it in no questions asked. It's one of those really important pieces of trivia that are vitally important to some few specialists, not so much for the world in general. For FSX, if you have an ECON setting, I like 63.Jeff ShylukAssistant Managing EditorSenior Staff ReviewerAVSIMP.S. @ j-mo:See? Reviewers do read the forum. Sometimes we even contribute.I'm not all that fond of your remarks regarding Angelique and Reviewers in general in the Reviews forum. You stated your opinion, and I 100% do not agree with it. I don't expect to agree with all of the AVSIM members on every single topic, so that's not a big deal in itself. I don't understand why people are needing to vent their spleens at Reviewers right now, there seems to be a lot of frustration out there. It doesn't at all seem constructive to me. Still, I can definitely speak for myself here: I spend way too much time reading and writing on AVSIM, and that's something I am proud of.

[Guest j-mo]

>Although from what I>recall (I could be wrong here), the pilots are just given a>number, and they plug it in no questions asked. It's one of>those really important pieces of trivia that are vitally>important to some few specialists, not so much for the world>in general. I read recently in a RW airline pilot's blog about an incident where, on a cross-country flight, the weather at their destination was deteriorating ahead of what was forcast, resulting in significant hold times for ariivals. This was going to put them in a significant fuel situation. The weather at their alternate was also deteriorating. While discussing options, the FO suggested lowering the Cost Index, which resulted in an acceptable fuel situation.=========================OTP.S. @ Jeff:The point of my other post was meant to be constructive. My intention was not to attack, but to try to stimulate discussion of a possible solution to general perception of reviews there. I strive not to simply complain, but suggest possible solutions.I meant no disrespect, and am sorry if it came across otherwise. I will monitor the other thread and say the same if others' perceptions are like yours.am